Traffic analyzer



April 12, 1960 w. T. o'NEll. 2,932,812

TRAFFIC ANALYZER Filed Feb. 24, 1956 9 Sheets-Sheet 2 April l2, 1960 W.T. NEIL TRAFFIC ANALYZER Filed Feb.y 24. 1956 9 Sheets-Sheet 3 April 12,1960 w. T. oNElL TRAFFIC ANALYZER 9 Sheets-Sheet 4 Filed Feb. 24, 19568949/933' 83080 WLS? MMU/7M gygy/252 A? rami-ff .W @NNN April 12, 196,0w. T. o'NElL 2,932,812

` TRAFFIC ANALYZEF Filed Feb. 24, 1956 e sheets-sheet 5 April 12, 1960w. T. @NEIL l TRAFFIC ANALYZER 9 Sheets-Sheet 6,

Filed Feb. 24. 1956 QQI April 12, 1960 w. 1'. o'NElL TRAFFIC ANALYZER 9Sheets-Sheet 7 Filed Feb. 24. 1956 INI/EN TOR, /HM n @WE/4 @frag/v5# famApril 12, 1960 w. 1'. o'NElL TRAFFIC ANALYZER 9 Sheets-Sheet 8 FiledFeb. 24, 1956 INVENTOR faeA/ff/ EWDN April l2, 1960 w. T. oNl-:IL

TRAFFIC ANALYZER 9 Sheets-Sheet 9 Filed Feb. 24. 1956 IN VEN TOR,WILLI/7M 7.' @W5/L 2,932,812 v TRAFFIC ANALrznn d William T. ONeiLVLaCrescente, Calif., assigner to Gilfillan Bros.,l Inc., Los Angeles,Calif., a corgrsorationV of California t l Y, Application February 24,195s, senarNo. 567,498

2s claims. (ci. :n0- 2.3)`

This invention relates to track-while-scan ground controlled approach(GCA) system andmore particularly to means for simultaneouslyYmonitoring the descent of a plurality of aircraft alongV the idealglidepath of. such` asystem. v

This application is a continuation-impart' of copending applicationSerial No. 476,467, entitled Traflic Analyzer, filed December 20, 1954now abandoned, by William T. ONeil. In the past, GCA monitoring systemsnormally have incorporated range indicators to produce-'aY display ofthe ranges of all aircraft being-guided bythe associated 2,932,812Patented Apr. l2, 1960 the range indicator merely by counting thenumbervof aircraft between the hazard aircraft and touchdown, i.e. whereaircraft are guided to land. By comparing this landing order with thevisual representations on the channel priority identification means, theidentity of the particular tracking channel toV which the hazardaircraft 1s assigned may be determined. Then a correspondingcommunication switchv may be operated to automatically or manuallyeliminate or initiate guidance of the hazard aircraft, or to change theguidance thereof as the case may require. Alternatively, the pilot ofthe-hazard Y aircraft may be warned by visual display transmitted fromGCA landing station to him or by vocal communication with him. t

According to a specific feature of the invention the channel priorityidentification means includes a bank or matrix of sensible means Yorindicator lamps with a f number of vboth rows and columns correspondingto the GCA system. Among otherV reasons, this display is pro- I vided tomonitorA the 'descent of anaircra'ft and thereby to detect any dangerousmaneuvers thereof which may constitute a hazard. In order that such ahazard may be removed ideally, an arrangement should be providedtoaifect selective communication to the aircraft causing Ythe hazard.That is, means should be provided to com- "inunicate with the pilot oftaparticular hazard.. aircraft to warn him and/or give him instructions.Alternatively, means might be provided to exclude the hazard aircraftfrom'guidance. It is thus'desirable that seltive communication besimply.I affected rather than effected although no convenient methodhas, to the present time,

been devised for this purpose.

The present invention overcomes this and other problems of the prior artby providing at least one manually operable switch identifiable witheachof a plurality of tracking channels in a track-while-scan GCAsystem. By

actuationof these switches, a monitoring system operator is permitted to`comnuinicate with any selected aircraft guided by the GSA system. Ifnoindication wereproduced with the yrange indicator display to identifyeach aircraft with a particular tracking channel to which each isassigned,l the monitoringV system operator would be required to actuatethe communication switches at randomV until he could communicate with aparticular aircraft causing a hazard to exist. For this reason, meansare accordingly provided inaccordance with the present invention forproducing visual representation identifying each tracking channel in thelandingV order of aircraft aircraft range indications and thereby thelanding order of aircraft. Since the communication switches are onlytion correlates the'relative range indication of a hazard aircraft onthe range indicator with a particular tracking channel so thatcommunication with the hazard aircraft.v

maybe selectively affected and a change in guidance thereof may beeffected Y by the aircraft.V

In order to monitor the descent of aircraft in accordoperator watchesthe range indicator. When he detects I 'a hazard beingv caused by aparticular aircraft', he may determine the landing order of the hazardaircraft' on total number of tracking channels in the associated GCAsystem. The rows may, for example, Ybe employed to represent differenttracking channels and the columns may be employed to represent thelanding order ofaircraft. Means are then employed to incandesce only onelamp in each row and column. A lighted lamp then denotes both thelanding order ofan aircraft and identifies the vtracking channel towhich it is assigned.

According to this same feature of the invention, a' communication switchis disposed in visual correspondence to each row of the indicator lamp.For example, each communication switch may be disposed in line with feach row of indicator lamps.. With this arrangement a switch affectingcommunication to an aircraft of a known landing priority may be quicklyfound by determining the row in which an indicator lamp is lit for thatvparticular known priority or landing order. t

' According to another aspect of the invention, a'novel device isprovided for operating thev channel priority lamp matrix. This device'may, in addition, be useful in a t number of other applicationsbecause, essentially, its function is simply to produce a plurality ofidentification signals successively in an Vorder corresponding to themagnitude of a common variable characteristic of a plurality ofcorresponding input signals.` In relation to the monitoring system oftheinvention, input signals are'gamplitude varying DLC. signalsrepresentative of the ranges of aircraft guided by the associated GCAsystem. These input signals are conveniently provided on separate inputleads because of the inherent `operational mode of the range trackingchannels of a track-whilev-scan radar system. Should the input signalsbe pulse amplitude, pulse width or pulse time modulated or be phase,frequency,

' or amplitude modulated A.C. signals, the device of the identificationsignals in an order corresponding to the I assigned thereto.. The rangeindicator Ynaturally provides to remove the hazardA caused ance with thepresent invention, a monitoring system the amount of modulation of each.

According to the invention the device employedV to produce theseidentification signals comprises -means for generating a comparisonsignal having the same common variable characteristic changing from oneto the other of predetermined limits, and means for generating anidentitication signal for each of the input signals each time the commonvariable characteristic magnitude of the comvcommon variablecharacteristic of the input signals, viz.

, paris'on signal becomes equal to that of each corresponding 'input'signal. In .the particular application of this device-to the lampmatrix, a plurality of orderregiste'rs are employed to provideselectively electrical paths to the lamps of the matrix. Each orderregister corresponds to a particular column, i.e. if columns areemployed to denote the landing order of aircraft. Each order register isthen operated by the *identification signals -but always in the samesuccessionregardless of which identification V means landing order in atrack-while-scan GCAy system.

this reason, means are provided "in accordance with the inventionto zeroand reoperate at the orderr registers only` when theftraic situationdoes change, .for example, `when assente kFor t l 'be any type of rangeindicator. The range indicator 12-A,

however; asv shown is vof the typetdescribed' in copending" ap plicationSerial No. 598,288,A ,entitled x Automatic an aircraft is initiallyguided or excluded fromguidance in they associated GCA system. It istherefore an object of raftalong theideal glidepath of agroundcoutrolled apn preach system.

n the invention-,to provideVV for monitoring the descentof aplnralityof.ain`

, 2li-A thereon on a time shared basis.

Vtarget spots ZZ-A are disposed in theelevation sectory ylit-Ato showtherangeof aircraft in a yGCA system as Another object of the invention isto provide means for quickly determining the channel offatrack-while-'scan radars'ystemtraclting the range of anaircraft'causinga hazard to others by a dangerous maneuver., y t

f It isstill another robject of the inventionto provide means forexpeditiously affecting with and/or affecting selectively an aircraftconstituting a hazard` in a t f vA further object ofthe inventionis toprovide means for correlating the tracking channel of an aircraft withits i a function of the elevationlof the aircraft. Target spots f callyr'eplresentthe range positionof` aircraft in the system f fas afunctionof azimuth. Q'I'he lines Zt-Afand `Zit-A Fig. 9y is a schematic view ofa lamp matrix and circuits t connected therewith; and

Fig. l0 is a block diagram of an alternative embodi-Q mentr of anotherspecific feature of the invention. y

- In the drawings in Figfl a panel lil-A containing inserts 12-A, 1,4-Aand 16A representing respectively a l range indicator,` a lamp matrixand a matrix of commnnry cation switches is shown. The rangeindicatorIZ-A may Ground Controlled .Approach Systems," filed December 15, 1953,by Horner G. Tasker et al. `The indicator 12-A 1 may bea cathode-raytube having appropriate circuitry to trace an elevation sector 18A andan azimuthsector t A` plurality of ,24-A in the azimuth ScfOrEZ-Aareemployed tov graphi- V are respectively' the ideal glidepaths,` ofaircraft in the sys-` A still further object 'of the. invention is toprovide, a j y' device for producing aplurality of identification sgnalssuccessively inan order corresponding ,to themagntudes of a commonvariable characteristic of a plurality of input signals.

Yet another object of the inventiony is tor provide means i. responsiveonly to changes in trafic conditions for zerorng devices registering theidentitiesof a plnralityof tracking channels ina track-while-scan GCAsystem in the landing,

order of aircraft assigned thereto.

Stillanother object of the invention isto provide means responsive tochanges in traffic conditions for, initiating the identification of the.landing order of a plurality of aircraft in a track-while-scanGCA-system with theparto land.Y Only thetlampl-A isflit in both 4eachcolumn;Y j

ticular tracking channels to which aircraft areassigned.

The novel features which are believed to be characteristic of theinvention, both as to its, organization and method of operation,together with further objects and advantages thereof, will be betterunderstood from the following description considered inconnectionwiththe accompanying drawings. It is to be expresslyunderstood, however, that the drawings are for the purpose, ofillustration and description only and are not intended as a definitionof the limits of the invention.

' Fig. l is a front view of a panel display of the monitoring system ofthe present invention;

Fig. 2 is a block diagram of one invention;`

feature. of` the present tern as a' functionof elevation, and azimuth.The. vertical lines 3ft-A and `:l2-A in the yelevation and azimuthsectors 18-A and 20-A are respectively employed to indicate equal rangemarks, the horizontal display being a logarithmic functionl tospaceaircraft closest to touchdown away fromY adjacent aircrafttso thatexamination may be t made of thefrelative position'sof aircraft about toland,

ie. those primarily vofinterest 'l t of abank of lamps 4 The lampinatrix14-Aconsists,

34-Aarrangedin an equalnurnbcr of rows and columns.

Arbitrarily the columns ratherthan the rows havebeen l. selected torepresent the landingy order of aircraft, the

left hand column being representative ofthe aircraft next and each row.For example, a lamp 36A islitfin the rst column andin the Vlast row,designated as row S. No other lamp 34A islit in the column 1 or. the rowS.

Five columns of' pushbuttons` are located in the panel insert 1,6-A. Thefirst column SST-A contains push-buttonsV corresponding to therespective rows offlamps 34-A to unlockrespective wave-off pushbuttonsv'-lO--A when an aircraft is waved-off, i.e. when an aircraft ismanually excluded from guidancein the associated GCA system. vSimilarlyan unlock column of pushbuttons `41E-A are provided` in the fourth rowfrom theleft. to unlock a plurality of voice pushbuttons 44-A Awhichmaybe employed for voice communication to aircraft corresponding to aplurality `of ltracking channels, N, O, P, Q, R, S. A single middle rowof pushbuttons 46-A are Vmomentary contact pushbuttons which may` beemployed to warn a pilot of Fig. 3 is a side elevation vlew of a Ledexmultiple switch employed in the invention and shown in explodeddiagrammatioform in other figures, as will be pointed out;

Fig. 4 is a partial diagrammatic and partial block diagram of orderregisters, whereat-two are shown in ex- K ploded diagrammatic form andtheothers `in block `diagram since all are of identical construction;

Fig.5 is a diagrammatical view of an acquisition detectoru and awave-otfdetector; 'l

l 1'1`ig`.,6 isA a diagrammatic representation' of ansawtooth y, t

generator in associated controlling circuitry;

` Fig.' 7 is a partial schematic view and block diagram ofY Schmidttriggers and associated relays, two being shown diagrammatically and theremainder, which are l videntical in construction, being in blockdiagram;

Fig. 8 is aschematic view `ofautomatic zeroing equipment and a masterorder selector;l

an aircraft assigned to aparticular'tracking channel that hrs posltionis hazardous to both his aircraft and aircraft i near him. For example,a warning light may be` displayed upon the instrument panel of anaircraft assigned to a particular channel. By virtue of the fact thatthe pushbuttons in the panel insert lt-A are in visual correspondence tothe row's..of the indicator `lamps 3ft-A, selective communication maybejmade to any aircraft, the priority or landing order of whichis known.

The monitoring system ofthe present invention-may bei usefully employedin. the following manner. A monitormg systemoperator may observe-theindicator 12A to detect a dangerous maneuver of` a particular aircraft.For example, if the aircraftrepresented by the third spot from the leftin the elevation sector 18-A may be tooclose `to the altitude or rangeof a spot corresponding to a Y Y tem operator may observe the thirdcolunmlnthe lamp preceding or subsequent aircraft. The monitoringsysmatrix 14-A, and find that the lampff-A in the first row N is lit `inthe third column.. This automatically tells the operatonthat to warn, togive instructions to, or tochange the guidance` of the aircraft:assignedl `to the tracking channel N. Aswitch corresponding tot a buttonin be operated. Forexample, if the Y the rowN must then operator wishesto communicate by voicewith the pilot of the aircraft assigned tothetracking channel N, the monitoring system operator may push theparticular lock voice pushbutton 48-A in the column 44-A. I-ftheoperator wishes to exclude the aircraft assigned to thecl`1annel N `fromguidance in the system, the pushbuttonS-A in the column Aiti-A may beYoperated. Again if'the monitoring system operator onlywishes to warn thepilot of the'aircraft assigned to the tracking channel N thatV he is ina dangerous position, momentarily the pushbutton 52-A in the column t5-Amay be operated. Thusa hazard caused by adangerous maneuver of anaircraft may be.. expeditiously removed.V

i With the six spots on the indicator 12-A, it will be ob- Served thatall .tracking channels are occupied This is not always necessarily true.All the smaller numbered columns l, 2 and 3 will contain an incandescedlamp so Vlong as thereare one, two. or three aircraft'respectively beingguided in the associated air'traiiic control system. Meansto operate thelarnp matrix 14-Av are described in the Figs. 2 through 9, inclusive.Fig. 10 isa block diagram of an alternative method of operating the lampmatrix 14-A and will for this reason be explained last.

The rst' embodiment of the present invention described herein wasdesigned for use as a unit in ra ground-controlled approach system forgoverning thelanding of aircraft at an airlield. yA signal channehis`assigned to each such aircraft andthe distance of each craft from' thefield is indicated by the magnitudev o-fY the range volt,-` age in itschannel. The range voltages. in the respective channels didersuccessively in steps'by any convenient number of volts, which forpresent purposes may be fixed at twenty volts. For convenience ofterminology, a channel carrying a range signal will be designated hereinas an active channel and one not occupied by a signal will be called aninactive channel. Operation is basically controlled and timed by asawtooth voltage that swings betweenl 25 volts positive and 120 voltsnegative.

The block diagram representation of the .present invention in Fig. 2shows the general. relationships ofv the several Vconstituent functionalparts. The reference character applied to ablock is -usually that of themost significant component of the part represented by the block as usedin subsequent detailed explanation. i,

`Range .voltage signals, each on an individual channel represented byone of .the letters N, O, P, Q, R, S, show by their Arespect-ivemagnitudes the distance from the` touchdown point of the aircraft thatis being tracked on the channel. if a channel is not tracking it carnes150 volts negative. These channels are shown applied to Schmidt triggercircuits to 140 and the trigger that is connected to a channel that istracking is made conducting by the rise ot' a sawtoothvoltage fromgenerator 11S. When the sawtoothvoltage `drops the channel having on itthe vsmallest range voltage, i.e. from the nearest craft, cuts od first,followed in the order of the magnitude of the range voltages byall otherSchmidt triggers that are tracking. The cut olf of each trigger blocks aswitch tube 141, 142, etc., which permits the fall-out of `a relayenergized when the switch tube is conducting. The fallout of each relaysends a recording pulse to a corre-v sponding contact in every one ofthe order registers. The master order selector is actuated by masterorder reset switch 123 at each rise of the sawtooth voltage to set up vcounter clockwise sense.

acquisition detector 73 which feeds an output voltage proportional tothe 'numbery of active channels into a diierentiator 87 that notes anyincrease in the incoming voltages and sends a lsignal to the standardgate generator 93, 94. The same channels feed into the wave-od detectorwhich'sends a signal to the standard gate generator when there is adecrease in the number of active channels. Wheneverthe standard gategenerator receives a signal, it passes it on to memory 161, 105, whenceit goes to a Schmidt trigger 104, then to sawtooth timing multivibrator199, -which activates the sawtooth generator 118.

That the recording pulses sent to the order registers shall not merelybe added to each other, but will in each instance reect the channel andorder of a recording pulse, each order register must be returned to zerowhen it no longer has a recording pulse impressed upon it. This isaccomplished by the automatic zeroing circuits to 174i which areconnected to receive the proportional voltage output of the acquisitiondetector so that as many of the zeroing circuits are energized as thereare active channels. Each zeroing circuit 165 to 170 is connected tocontrol a specific order register and each zeroing circuit is biased tooperate at a definite number of channels, e.g.,.165 operates when thereis only one active channel, .165 and 166 when there are two, 165, 166and '167,when there are-three, etc. Each zeroing circuit leaves-itsregister free to respond to recording pulses whenfthe zeroing circuitvconducts, but holds the register zeroed when it is 4notconducting. Thusthere are as many registers channels.

selector and as order registers in the present invention Yismanufactured by the C. H. Leland Company of Daytom-Ohio, and is soldunder the trade name of Ledex.

4 ltcomprises a rotatable shaft 20 mounted in end brackets 21. rUpon. astub shaft 22, rotatably mounted in the housing of solenoid 23, is anend plate 24 having a drivingl connection with the stub shaft 225.' Thesolenoid 23 exerts upon the end plate a powerful tractive effort whenenergized. Between the end plate 22 and the housing of solenoid 23 arethree equally spaced ball bearings 25, mounted in a substantiallyhemispherical cup in the housing of the lsolenoid and riding in arcuategrooves in end plate 24, the depth of the grooves increasing in theThus, when the solenoid is energized and the end plate is drawn towardit, the reaction of the balls 25 with the .inclined plane bottoms offthe grooves applies a torqueto end plate 24 that rotatesthe end plate,and consequently shaft 22, in a a return circuit from the iirst orderregister so when it receives the recording pulse it is actuated toindicate i the channel received by the trigger that initiated therecording pulse. After each recording pulse the master Vorder selector.is movedone step to establish a return circuit from the second orderregisterythe third order Y register, etc., each i'n turn. l l Y lt isnot necessary that the sawtooth generatorvnun continuously, Vbut onlywhenthere isa changem the number' clockwise direction as seen fromtheleft hand end of the device infFig. 3.

' Fixed to the contiguous ends of each of shafts 20 and 22 is arespective metal disc having portions 26 and 27 struck out to extendaxially to engage each other and V'form a ratchet to drive shaft 20 whenshaft 22 is rotated.

A calm 28 is carried-by the above-mentioned metal disc on shaft 22 tomoveaxially with and to rotate with that shaft as end plate 24 is drawnin and rotated by solenoid -23' and near the end of its movement cam 28moves underspring leaf 29 that carries a contact point 30 and lopens thecontact, thus breaking the supply circuit to solenoid 23, as will bemore fully, explained hereafter.

-A returnspringtnct shown) then pulls end plate 24 and shaft 22 back totheir initial positions.

The rotary switch also includes a plurality of wafers 32, 33, .'34 and35 ofinsulating material mounted concentrically with shaft-20 onlongitudinal rods 36 with spacers 37 between each two wafers. Referenceis now made .to Fig.` 4 `wherein isshown a Ledex in exploded free torespondV as there are activey register, and so on.

diagrammatic form, the parts` being given the same reference characters`as in Fig. 3'` but followed by (-1), (-2), (-3), etc., in eachV casewhere shown in the diagram to indicate the order register underconstruction. Conductive rings 38 and 39 are insulatingly mounted onshaft 29 centrally of and coplanar with the right-hand face and theleft-hand face, respectively, of wafer.321. it will be noted that eachhas a peripheral cut-out portion, identified respectively byl-i and 41.Wiping contact 42 fixed to wafer 32 extends radially inwardly beyondcutoutllV and makes continuous contact with ring- 39 and is connectedto` contactblade 291so that so long as current is supplied to ring 39the solenoid 23-,1 willbe energized eachpiV time the contact pointsclose after thereturn movement lof end plate 24 and shaft 22 and willcontinue to step shaft 20. Contacts 435Y tol, both inclusive, wipe ring39 adjacent its periphery so. that they are out of contact with theVring when cutout 41 portion is in registry with theangular position ofany of the contacts ofthe group. It is apparent that if one ofthecontacts 43 to `43 is connected to a voltage supply solenoid 23-1 will..continue to step shaft'Zll until the cutout 41 is'moved to thepositon ofthe live contact, at which time the circuit will be broken and the Ledexwillrbe horned on that contact. There must of course be a return path tocomplete the circuit through solenoid 23-1 in order for it to function.How and when such return pathis established and how and when'theVcontacts 43Uto 48 are energized will be fully explained hereinafter.

The two rings 38 and.39 are conductivelyconnected together asindicatedby element;49. The -only'effective contact that;` wipes ring3:8is designated 50v and is connected to the `automatic zeroingcomponent, to be later described, andfthusf maintains a voltage supplyto solenoid 23-1 until cutout 40 reaches the position of 50, at whichtime the rotation of shaft Ztl is stopped. Examination of the drawingmakes it apparent that when` rotation of shaft 20 is stopped by contact50 being in cut- Y out 4t), the cutout 41 is in position to begin movingacross contacts 43 to 48 at the next step of rotation of shaft 20.Hereinafter the device willbe said to be zeroed or in zero positionwhenl the conditions just `described prevail.' Thepzeroing pulse tocontact 50 is never simultaneous with the energizing of any of contacts43.

to 48.V The L'edex shown in Fig. 4 and in part described above is termedan order register, havingrthe function of respondingV to the rangevoltage from a` designated channel to-show channel and priority order ofthat channel, as will be fully explained. There will be as many order.registers as there are channels to be tracked, conveniently six,although all are notshown in detail in the present drawings because theyare identical in structure and function with those shown and de-E,

scribed. The name order register is used `since the signal derived fromthe. channel having the first `order of priority of landingistransmitted to therst Vorder The order registers the proper sequence bythe master order'selector. It

will be recalled that solenoid 23 of `a Ledex can oper-V ate only if avoltage return `connection is provided. The

function vof the master order selector is to establish such! returnconnectionsrto, the order registers in the sequence of their ordinaldesignation first, second, third, etc. The

manner of establishing the return connections will now be set forth.

The master order selector is likewise a Ledex but with-the connectionsmade to perform its particular functions. As shown in Fig. 8, thesolenoid 23-7 may be .energized byvcurrent. through rings 3S-7 and39;-7, the latter being fed directly through lead 51 so long as itscontactis not in cutout 41-7 and ,through connection of 49-,7 from 385-7when it Conductive ring 53`7 is insulatingly mounted on the same shaftas rings 38-7 and 39-7, but instead` of a cutouty portion itihasdavpro-l `this current-doesnot pass` breaker contact 279-.-7V but onlythrough the solenoid to j common lead returnv57 and so can rotatethe`shaft but iecting tab 5de-1" thatwipes the annular series oieontact'disposed around it..

Two i. diametrically opposite contacts designated Ol have no conductorconnected to them but the five contacts shown onone sidel of thediameter between contacts Ol are connected to lead 51 whilentliose onthe other side of that line are connected to ring 38-7 by-lead 49-7. Therising positive edge of the sawtooth voltageY closes a contactto supply28 volt current to ring 52%;7A through lead v56-so that so long as.tab541touches any other than one of the O1 contacts while the 28 voltsis thusv applied-current will ilow to solenoid Z3-7 throughrings 38-7"and 39-7 and con-` tact spring'blade 29-7 'to 28 volt common lead 57 andthe 4Leden will be stepped until` tab 54 reaches one ofY index pulse.TheidesignationOl Yis used since when ring 53-7 is in` that positionthemastcrorder selector is set vto condition order on'e-v order register(rst order register) to function, as willv befexplained. It is apparentthe master order selector Ledex will always stop in position toVcondition the first order register `after each rise of the sawtoothvoltage, and it is then said to be homed on the first order register.Solenoid 23-7 is energized directly through lead SSaftereach recordingpulse signalffrom an active channel. It will be seen that through ring39-7 and the.

one step -regardless of how long. it isapplied.

Insulatingly mounted onthe same shaft as rings 38-7, 39-7 and 53-7 isanother conductive ring`59-7 similar to 53-7 with aperipheral tab 60'.`i Disposed around ring 59-7 is an annular: series of contacts`designated Ol', O2, O3, 04, O5', and Q6, the diametrically opposite`ones being given Athe same numeral because they are connected torespective common leads 61-1, 612, 61-3, lt-4, i1-5, and` 61-6 that arerespectively in the return` circuits from the solenoids of orderregistersl to 6. A

` lead 62 is continuously connected to ring 59-7 and,

through a relay 149 that operatesat the properV moment (to beexplained), completes the return circuit from the order registerconnected to the contact that is at that instant touching tab 6i). Itisapparent that no matter which `half-rotation the ring 59-7 has justexecuted the return path from the first order register will beestablished through Y lead 61-1, one of the contacts O1', tab 66, ring59-7 and lead 62 ready to permit the first is received by it and theVabovementioned relay closes. Likewise in turn,

` the second, third, etc., order registers will be conditioned forresponse in their turns as ring 59-7 is rotated one step at a time tocause tab 60 to wipe contacts O2, O3, etc., seriatim.

The generation of the before-mentioned sawtooth volt-` l age isdescribed as being initiated by a signal derived from changes in therange voltage channels, but it is to` be understood that it can as"wcllbe done periodically by any of the well-known electronic or mechanicaltiming devices, or even manually; For purposes of description it isherein assumed that there `are six range channels available for feedinginsignals, which channels may be considered as respectively coming in onleads 63, 64, 65, 66, 67, and 68 (Fig. 5). VEach of these leads feedsinto one terminal of the primary of a transformer 69,. 70, etc., withthe other terminal of the-primary grounded through an adjustableresistorll, 72, etc. The secondary circuit of each transformer includesa respective diode 73, 74, etc., and a load resistor', .76, etc. The

adjustable resistors inl the primary circuits are set so,

lead 77 the voltage in lead Y V'77 lwill be 10h, where nis theA numberof active channels. By virtue of the rectifyng DC. voltage whenrequired. The diodes, transformers,

and load resistors just described are collectively designated theacquisition detector since each time a theretofore in'- active channel,Vbecomes active another diode is caused to conduct and a l volt increaseappears on -leadY 77.

The range voltage leads 63 to 68 arelalso. eachrespectively connected tothe cathode ofa diodeSO, 81,

etc., whereof the anodes are connected to `ground through' respectiveresistors 32, S3, etc., and to aY common output lead 34 through arespective capacitor 85, 86, etc. When wave-oit occurs, i.e., atheretoforei active channel becomes inactive, for any reason, the rangevoltage signal is replaced by 150 Avolts negative Vand the cathode ofthe diode 80, etc., that is connected. to 'that channel will becomestrongly negative, the diodejwill conduca-and a negative pulse will besent through; capacitor A85, etc., as the case may be to the common lead84. This group of diodes with cathodes connected Vto the range voltagechannels is collectively termed :the wave-orf detector, for

reasons that are apparent.

Lead '77 from the acquisition detector is directly connected to the gridof a triode 85 (Fig."6) which is connected as a cathode follower byleadV 86 to the grid of triode 87 and so thel signal on thegrid oftriode 85 is isolated from the following circuitry. Each l0 Voltincrement of voltage on lead 77 .due to the acquisitionA of anotheractive channel causes' an increase in thecurrent through 37 which thusYsends out a negative signal through capacitor 8S to the cathode ofdiode 89.` Triode 87 functions as a differentiator since plate currentcan liow only when the grid-to-cathode follower differential is greaterthany cutoff. Resistor 90 is so large that the plate current it permitsto flow may be neglected.

Output lead S4 from the wave-off detector is yconnected to the cathodeof a diode V91 whereof the anode is connected in common with the anodeof diode 89 to a lead 92 so that an' increase in the number of activechannels produces in lead 92 a signal derived from the acquisitiondetector and when there is a decrease in the number of active channels asignal is put on lead" 92 from the wave-olf detector. triggers amultivibrator comprising triodes Y93 and 94,

termed the standard gate generator,` that produces a pulse ofsubstantially constant duration and amplitude that Vis applied to thegrids of triodes 9S and 96 via lead 97.` The cathodes of triodesY 95 and96 are connected 'to ak common output lead 98 to function asa cathodefollower. The ,values of capacitance 100 and resistor 99 are such as vtogive a large time constant for the' discharge of the cathodes of triodes95 and 96 so that the absolute value of the time constant is notcritical and variations due to such causes as humidity are relativelyunimportant. the maximum The signal impressed over lead 97 exceedspositive grid signal for triodes 95 and 96 for high impedance gridconditions so the cathode fol-V lower is forced to operate at zero biasduringthattime, which results in rapid charging of capacitor 100. Afterthe signal is terminated the cathode potential of 95 and 96 remains highand can discharge only'throughjresisftor 99. Triode 101 is a D C. levelshifting device and high impedance load for the cathodes of triodes95and96 and has in its cathode circuit a is connected to the grid oftriode 103 in Schmidt trigger 104. Y

The threshold Voltage above which triodes`95 and 96 The signal on leadY92 voltage divider 102-that v fire is such that a single cycle' ofoperation of these tubes is suflcient, because of the long time constantof.`

the"R.C. combination 99 and100, to holdSchmidttrigger Vorder selectorLedeX.

spcctive'precision divider 130 (Fig. 7)

A200 volts at a distance of ten v combined range signal and the sawtoothSchmidt trigger 104 is employed. The output of trigger 104 is applied tothe grid of triode 105 which is con-L nected to function as a cathodefollower to apply its output to thevscreen grid 106 of pentode 107which, with pentode 103 and the interconnecting circuitry, constitutes asawtooth timing multivibrator 109 having a natural period of tenseconds. The on-of control applied to the screen of triode 106merelystarts and stops it, thus permitting several free running cycles pertiring of the standard gate generator 93, 94 when a signal is receivedfrom either the acquisition detector or the wave-ofi derector.

As multivibrator 109 free runs relay 110 is alternately energized anddeenergized. When this relay is energized the contacts 111 and 112 closea circuit from 150 volt source 113 through capacitor 114 to charge thelatter, While contacts 115 andrll close a circuit from capacitor 17through sawtooth 'generator pentode 118 to discharge theifcapacitor 117through tube 118. f When the relay is deenergized contacts'111 and 119close to discharge capacitor-114 through pentode 118 while contacts 115and 25,0 close a charging circuit through capacitor 117. The alternatedischarge of capacitors114 and 117 through sawtoothgenerator 118Yproduces the sawtooth voltage, which runs from 25 volts positive to 120volts negative, for timing and controlling the operation of the system.Adjustable resistor 120j provides for controlling the slope ofthesawtooth voltage. Pentode 118 is operated de-v generatively to giveconstant current discharge from the capacitors 114 and 117.v Triodes 121and 122 are connectedin the output circuit of pentode 118 to operate asa cathode follower and provide alow impedance output from the pentode,andfrom hence alll the applications of the sawtooth Voltage are made.

One output from triodes 121 and 122 goes to the master order selectorswitch 123 wherein the triodes 124 and 125 are normally vcut olf, butthe rising positive edge of the sawtooth voltage places them inconduction, thus energizing relay 126 to close contacts 127 and 128 andput 28 volts on lead 56 and hence on ring 53*7 of the master A As beforedescribed, this will energize solenoid 23-7 and keep the master orderselector in rotation until ring 57 homes on one of the contacts v 01, inwhich position a return is established through lead 62,ring 59-7 andone'of the contacts Ol. to the solenoid. 231 of the rst order registerand' that register is then conditioned to respond to the iirst rangevoltage channel that sends out a signal, in a manner to be described.

Another output ofvsawtooth voltage is put on lead 129 whichis connectedin common to the midpoint of a rewhich'has a terminal in the free gridofzone of the triodes 131, 133, etc., of Schmidt triggers 135, 136, 137,168, 139 and 140. Schmidt 'triggers 135, etc., are designed to fireVnear ground potential on their free grids. The other terminal of eachprecision divider receives the signal from a Yrespective channel at alltimes. -When a channel is inactive, it,puts out a slightly negativerange voltage. The range voltages vary from 0 at the point of touchdownto miles. The grid voltage applied to each Schmidt trigger `is theresultant of the voltage, the time between rising edge and rising edgeofthe latter being on the order of twelve seconds, determined by thecircuitry thatV influences the operation of sawtooth generator 118, asabove described. The maximum positive voltage of the sawtooth issulicient'to pla'ce any of the triodes 131, 133, etc., of the Schmidttriggers in conduction if the range voltage for the particular channelis between 0 and 200 volts, i.e., if the particular channel is tracking.Howeven'if a particular channel is not trackin the 20 volts 100 hasfallen to a small frac f of triode,152 holds it i order register.

ll positive maximum will. notA iirethetriode 1,31, 133, etc., as thevcasemay be. The maximum negative amplitude of the sawtooth, 120 .v olts,isfsuicientto drive any Schmidt trigger below the conduction point' andcause it. to drop out under all tracking circumstances up to 200rvolts.The range channels will for convenience be designated by the letters N,O, P, Q, R, S.v

Assume that range channel S is connected to the grid of triode 131 andchannel R is connected to the grid of triode 133 and that .the aircraftbeing tracked by channel R is nearer than the craft on channel S, thatis, channel R has landing priority overchannel S and the range voltageon channel R is less. As the sawtoothA voltage rises both of triodes 131and :133 will be thrown intoconduction, which will holdtriodes 132 and134 in` Schmidt triggers 135 and 136 cut off. 'Ihus triodes 141 and'142whereof the grids are connected to the anode `supply of triodesY 132andA 134 will be conducting and relay solenoids 143 and 144 connected inthe anode supply of` the last-mentioned triodes will be energized. itshouldibe noted that the correspondingtriode connected to each of theSchmidt triggers`135to :140 isznorrnally conducting `so that therespectively connected solenoids` are energized and the contacts 145and-146 iny each are closed to place 300 volts from source 147 via lead14 on the grid of triode 148 which has connected in its cathode circuitby lead 58 arelay149, Figs. 2 and-8,'that, when energized, openscontacts 150and 151 and so prevents the establishment of a return pathfrom any order register via lead 62. When any one of relays 143, 144,etc., is deenergized the 300 volt potentialto the gridof triode 148 iscut oil and the t return paths may then be established.

The 300 volts are also appliedto the grid" of triode 152 which draws itsanode supply through solenoid 153 which closes contacts 154 and 155 andputs 28 volts on 1e'ad56 which thus suppliescurrent to ring 53-7, thencetoring 39-7 and solenoid 23-7 of the master order selector to advancethe selector one step. The RC, combination of capacitor 156 and theresistor conducting for a suicient time` to insure that the stepiwill bemade. s

When the sawtooth voltage decreases triode 133 that carries the signalof channel R will cut E first since the therange voltage of channelj Ris less. When tube` 1313` cuts off its anode voltage rises and this riseis transmitted to the grid of tube 134- and causes that tubey toconduct. The drop in the anode voltage of 134 when it begins to conductis applied to the grid of 142 which cuts Voti the latter, deenergizingrelay 144, cutting ol the 300 vvolts to triodes 148 and 152, andpermitting contacts 158 and 159 to close to put 28 volts from lead 160cmthe contactv 44 of each order register when solenoid 161 is notenergized. This 28volt signal is termed the recording pulse. As aboveexplained, the master order selector is homedby each rise of thesawtooth'voltage to establish a return from the first order register, sothat the rst o rder register will now be stepped until the cutout'portion 41 of ring 39 cornes to the position of contact 44, when therotation will stop. Since all the leads N,'O, P, Q, R, andS from theSchmidt triggers and associated relays are connected to conductive rings39, 39-2, etc., in all registers the unidirectional conductive devices210 are u sed in the leads to prevent feedback. Likewise, if channelS issecond inr priority of landing triode 131 will be next `cut off; whichwill result in the cutting off of triode 141, thedeenergizing ofsolenoid 143 and the placing of a signal on the contact` 43 of each Whentriode 142 resumed conduction after the recording pulse to the contacts44 of the order registers, the 300 volts to triode 152 caused theenergizing of solenoid 153v which placed a 28 volt stepping pulse onsolenoid 237..of the master order, selector via` lead Maud-.rotated theselector onestep so that areturnpath the respective 157 inthe` gridcircuit,

. channels.

, channels.

- Due tothe complete reappralsal of the tral'iic situation l2 was then.,established from the, second order register.` Therefore, the. cut-out'41 is at the position ofthe contact 43 thereof and the rotationwill-,then stop.

The same sequence.` is followed through all the active As the Schmidttrigger corresponding to each of the various channels is cut ot arecording pulse will be: sent to'` all the ordery register contactsrespectively connected to each Schmidt trigger and the master orderselector provides in turn for a return connection to each of the` orderregisters. It is to be understood that this is repeated each cycle ofthe sawtooth voltage.

It will be recalled` that the vsawtooth generator does not runcontinuously but only when set in operation by a signal` derived Vfromeither the acquisition detector or the wave-off detector. The reason forthis is that so long as there isno change inthe` relative status of theactive and the inactive channels no useful purpose is served bycontinuous running ofthe-sawtooth generator but there would be thedistinct disadvantageof` unnecessary wear .on the equipment andfatigueofpersonnel by theclatterysawtooth generator is started and the. wholesituation is analyzed and priorities assigned to the several then activepresentedby the range voltage channels at each rise of the sawtoothvoltage and the fact that there frequently are changes in the trahiesituation, it is necessary that:

each order register be returned to zero each cycle so that ity will beable to respond accurately to any signal sent to it. The automaticzeroing component now to be described isY provided for that purpose.thyratrons tof170, equal in number to the number ofr range channels(Figs. 2 and 8). That the response of the zeroing means may beproportioned to the nurnber of active channels the t0n volt signal fromthe acquisition detector is applied to lead 171 by which-it is' put.onfthe grid of tube 172 (Fig. 8) when contacts 173:'and 174 are closedby conduction of tube 148 when' the 300vo1ts are on its grid at. thetime all the relay solenoids` 143, 144, etc.f,. are energized, i.e.,when no recording pulse is acting on any of the order registers. The-Voutput of tube 172 is proportional to lOn and is applied as a cathodefollower to constant voltage device `175 which 'holds its outputuniformly at 87 volts below the voltage of the cathode of tube 172 andthis is applied through conductor 176 `to thegrids of thyratrons 165 to170. `An, alternating-voltage is` also applied` to the grids of thethyratrons from lead 177 through the respective voltage dividers 178,`179,A etc., with thyratron 165 biased so it will relwhen only onechannel is tracking. The A.C. voltages on the gridsl of theseveralthyratrons differ by increments of ten voltsso that when twochannels are tracking both 165 and 166 will fire, if three channelsare-tracking then 165, 166y and 167 will all re, and so on for the totalpossible number of channels. An alternating potential of volts is put onthe plate of each ofthe thyratrons 165 to 170 from lead 181 throughrelays 184, 185, etc., and the respective capacitor 182.

After each recording pulse all the relays controlled by theV Schmidttriggers 135, 136, etc., are actuated to place 300volts on tube14S-which energizes solenoid 183 that closes contacts.- 173 and 1747toput the voltage derived from the acquisition detector on the grid of thetube 172,

` thence to device 175 `and to the grids of the thyratrons to the activechannels to re.

the tirst order register until cut`out 40 is opposite contact 50, whenthe circuit is broken and the rotation stops as previously mentioned.The zeroing lead from contacts 188,r 189. to.. second order, register is253; ln.` like the second order register will `now rotate until,`

This includes v Y contactst145, 146V open so that the vfrom tube 148 andthus solenoid 183 is deenergized andv contact 180 to place Ymanner'eacvmv thyratron controlsy a zeroing circuit. Each thyratron thatiires energizes the respective solenoid 184, 185,/ etc., its platecircuit and opens the circuits at contacts 186, "187 and 188, 189, etc.,respectively Acontrolled by each solenoid 184, etc. Withholds the 28volts onlead 190 Yfrom those order registers that are horned on achannel but since the solenoids associated with any thyratrons that didnot lire are not energized the 28 VoltsV in lead 190 is applied to theorder registers corresponding vto the non-lired thyratrons to zero theregisters. Y N l When tube 148 lconducts the diode 191 also passescurrent, energizing relay 161 tosclose contacts 192 and 193 and connectlead 190 to the28 volt source. While diode 191 conducts the capacitor194 is charged and Vafter* conduction by the diode ceases capacitor 194must discharge through solenoid'161 as it cannot discharge back throughthe diode. This delay `in cutting o the 2.8 yolts `from lead 190 insuresthat Vall registers correspond- -ing to inactive channels willbe zeroed.vEnergized solenoid 161 also closes `contacts 195 and 196 which providesa return for the order registers being zeroed through lead 197andtcontacts 198, 199 which are closed in each relay associated with atron 1165 .this return circuit includes-lead 200 and lead 61-1, fromthyratron 166, leads `202 and 61-2, etc. It is to beunderstood that thecorresponding connection from thyratron 166 to the second order registeris along leads 202 and 61-2 fromthyratron 167 to the third orderregisterl along yleads 294V and 61-3,` etc.' Y

f When any one of the Schmidt triggers 135 to 140 is Vcut off therespective solenoidV 144, 145, etc., controlled by the Schmidt trigger,Athat cuts Ioff is deenergized, a recording pulse is sent to therespective order register and the 300 voltsis cut off contact 174 closescircuit through on the grid of tube 172 a bias from divider 207 voltsource 208. lThis bias is great enough so voltage applied to the gridsof thyratrons 165 causes them all to lire,

and 150 that the to 170 etc., and so all the order registers are freetorespond toa'recording pulse if it comes. It will be recalled thatarecording pulse is sent out each time any Schmidt trigger cuts oli. Y

t When the 300,Volts removed diode 191 ceases to conduct and after thedelay due to capacitor 194 the solenoid 161 is deenergizedwhich permitscontact 193 to close with contact 209 and connect lead 160 to plus v28volts which is thus supplied to the recording pulse relays 15 to 20 fortransmission to the respective order register as the correspondingSchmidt trigger may cut ofi. Although there is a delay in supplying the28 vol-ts to the recording pulse relays after a Schmidt trigger cuts oi,due to capactor 194, the RC combination of capacitor 211 and high valueresistor 212 (Fig. n7) keep tube 141 cut off for suiiicient time for theconnection to be made and the recording pulse transmitted as called.for. It is to be understood that each tube analogous to tube 141 incircuit with a Schmidt trigger has a like RC combination.

AThe data derived ifrom an analysis of the trafiic situation accordingto the present .invention are primarily intended for use in groundcontrolledapproach systems but the manner of their application for thatpurpose is beyond thescope of this disclosure. However, it is desirableythat personnel operating the present invention be able to check on thefunctioning'of the apparatus and for this reason means are provided togive avisualsignal thyratron not iiringrfrom thyra-J energizing thesolenoids 184,` 185, etc., 4and thus breaking the zeroing circuits tothev order registers through contacts 186, 187 and 198, 199, Y

' register, e.g., 53-1 as shown in Fig. 9 with associated electricalwiring. Each order register has a conducting ring-designated by 53followed by a numeral showing the order of the means conducting transmitring of the first order register. rlfhe transmit rings are fixed on theshaft of theregister tofrotate with the rings 38 and 39. Lead 214Icontimlously supplies 6.3 volts A.C. to the transmit rings. v Aroundthe transmit ring 53-1 are contacts connected to leads MNI (MN followedby Roman numeral one), MOI, MPI, MQI, MRI, and MSI, disposed to becontactible by tab 54-1 on ring 53-1. The designation MNI, etc., is usedto show that the lead so identied connects the lamp matrix to the Nchannel at the flrst order register, MOH connects the O channel via thesecond order register -to the matrix, etc. These contacts are soarranged angularly that when ring 39 is homed on contact l48 (channel N)the tab 54-1 will close the circuit through `contact for lead MNI which`will light the lamp in the top horizontal row and in the left handvertical row, showing that channel N has first priority of landing. Thelead 215 is the common return.

from all the lamps. In like manner, if the ifth order registeris homedon channel Q, the lamp in the fourth row down from the top and in thevertical row fifth from the left will belighted to show that channel Qhasl the iifth priority order to land. There will be such a visualsignal for each channel that is tracking to show What'the landingpriority order for each respective channel is.

The same leads that carry signals to the matrix are connected to otherutilities employed to convey' the necessary landing priority informationto` pilots, such as ground controlled approach (GCA), but that equipmentis beyond the purview of this disclosure.

i An alternative arrangement for the Schmidt triggers 135'through140 andthe switch tube and relay combinations 15, 141,16, 142, etc., is shownin Fig. 10. This arrangement is employed to produce output pulses or.identiiication signals when the phase of-.a phase modulated oscillator12-B exceeds respectively those of alternating input signals N, O, P, Q,R and S. i

A modulation signal source 10-B there shown may V"be employed to producea sawtooth voltage to vary the that shows uniquely for each recordingpulse the channelthe landing priority phasefofl the modulated oscillator12-B linearly in response to anpinput pulse indicating a change intrafiic conditions. Phase detectors 14-BN, 14-BO, 14-BP, 14S-BQ, etc.,are employed to compare the output signal of the phase modulatedoscillator 1ZB with the A.C. input signals N, O, P, Q, R and S. Y Clamps16-B andv 16-BO, etc., are connected to the output of the phase detector14B to clamp the output thereof to, for example, ground when the outputsignal of the phase modulator oscillator 12-B is, for example, less thanthat of the input signals. When the phase of the modulated oscillatoroutput signal exceeds that of an input signal, an integrator 18-Bcorresponding respectively to the particular phase detector 14B isemployed to produce an output pulse or identication signal. Similararrangements of course may be made with frequency or amplitude modulatedalternating signals or pulse width, pulse amplitude or pulse timemodulated pulse signals. 'l

What is claimed is: v l

l. In an aircraft landing signal system, a unit for determining theorder of landing of several aircraft to each of which is assigned arangefsignal channel, cornprising a respective electronic trigger havingtwo tubes with the grid ofthe iirst tube of each trigger connected toreceive a respective signal channel, means to generate f and supply tothe grid of each first tube a sawtooth voltage of predetermined durationper cycle having a suiiicient positive amplitude to render conductingeach first tube which has a range signal impressed upon it and ofsuicient negative amplitude to cut ofi all the first tubes even thoughrange signals are impressed, said tubes being thereby successively cutott in the order of increasing signal strength. in the respectivechannels; a respective order register assigned to each priority oflanding, each register having a respective input contact correspondingto each channel and connected to receive a signal derived from cuttingoftr the said first tube of thetrigger in that channel, a rotatableshaft and fixed thereon a substantially annular conductive memberdisposed'to touch said contacts but having a cut outportion that is inturn brought into registry with each contact as the shaft is rotated, arespective output contact for each channel, means fixed on the shaft tobe rotated into position to energize the output contact corresponding toa horned input contact; electrical means-to rotate the shaft whereof thesupply circuit4 includes. at least one of the.input contacts, theannular member and a return path; means to control the rotation oftheshaft by steps having an angular magnitude equal to the central anglebetween adjacent contacts whereby when. rotation of the shaft brings thecut out portion to an energized contact the supply is interrupted andthe register is homedon the channel represented byV the contact atthecut out portion; means controlled by the rising voltage ofeach sawtoothcycle to establish a return path from the shaft rotating means of therst order register; means responsive to signals derived from cutting offthe first tubes to establish return paths from the means to rotate theother register shafts in a succession deiined by the ordinals of therespective registers; andv means connected lto all theregisters toconvert into usable signals the outputs from the registers to show thechannel and priorityv order defined by the horned position of eachregister.

2. A-unit as set forth in claim `l that also comprises means connectedto receive incoming range voltages and conditioned to be responsive to adecrease in the number of channels receiving range voltages, other-meanslikewise connected and conditioned to be responsive to an increase inthe number of such channels, and circuitry4 connected to beactivated bythe responses of either of the'next preceding two means to produce asignal to ini-A tiate generation of the sawtooth voltage. 3. A unit asset forth in claim l, also includingmeans lb respective means responsiveto the range signal in each channel, the signals each having strengthyproportional to the distance of the aircraft represented by suchisignal,means to extinguish cyclically the response of each'first-f mentionedmeans inthe order of increasing signal strength. thereon, means toderive apulse from each channelass` the signali isfeX-tinguished,individual means' to receive, and record the pulse from' each channel,`and means to` directto the same pulse-recording means the `pulseresulting from the first-eating,uishedichannel, to another same pulse-Arecording means the pulse from the second-extinguished channel, and soon, regardlessof which specific channel may be lirstor secoii-extinguished, and so on, in each` cycle. r i Y 6. A unit as set forthin claim 5 that further includes means to generate a sawtooth voltageand means to apply that voltage to extinguish lcyclically-the responseto the range signals. 5; A 7. A unit as set forth in claim- 6" thatcomprises alsov means responsive to a change in the number of chan-.1nels carrying range signals to initiate generation of the sawtoothvoltage.

8. A unit as set forth in claim 5 that further comprises means to returnto zero positionfany pulse-record-` ing means when it is 'notfunctioning -to record a pulse.

9. In a system for controlling a plurality of aircraft, the combination'comprising: a separate channel` corre'- sponding to each aircraft, eachchannel being `adapted to produce an output signal in vaccordance withthe position of each correspondingaircraft, all of said channels beingoperable to produce signals having a predetermined common"l range ofvalues, whereby any channel may be as-V signed to any aircraft having aposition falling within aA channels for producing position indicationscorresponding to the relative positions of all of said aircraft, eachfposition indication not only corresponding to a particular to produce avoltage proportional to the number of active range channels, meansconnected to receive the proportional voltage, which last-mentionedmeans comprehends individual electrically conducting devices equal innumber to the total number of` channels, each device being conditionedto respond to a respective level of the proportional voltagecorresponding to an assigned `number of active channels so that thenumber of devicesY conducting at" any time is equal to the number ofactive chan- Y nels, a respective relayv connected to be closed bycurrent through each device, means connecting each relay to a voltagesupply, meansconnecting each relay to a respec-A tive order register,thetrelay connected to the device that conducts at a signal level of oneactive channel being connected to the iirst order register, the relayconnected to the device that conducts at a signal level of two activechannels being connected to the second order register, and so on throughthe series, the contacts of the relays being so connected that when therelay is not energized it applies the supply voltage to its respectivelyconnected order register to move that register to and hold it in zeroposition, but when energized that voltage is withheld from the orderregister so the registeris free to respond to a pulse derived from arange voltage signal.

aircraft, but i lso thereby corresponding to a channel assignedVthereto; means also responsive to said channel out- 'put signals forproducing additional `indications identifying saidchannels in positionsspaced apart ina predetermined direction and in the same orderlas theorder of appearance of respective corresponding position indications onsaid cathode-ray tube; and circuit controlling means identifiable witheach of saidchannels to ele'ct communication with each correspondingaircraft."Y

10.`In a track-while-scan landing systemV for controlling the descent ofa plurality ofaircraft along van ideal' glidepa'th, `said system havinga channel for each of said aircraft to track the range of each and anindicator for producing a visual representation of the range of each ofsaid aircraft, an arrangement to monitor simultaneously the descent ofall of said aircraft, said arrangement comprising: a bank of sensiblemeans actuable to indicate visually the, identity of said trackingchannel in the landing order of aircraft assigned thereto, said sensiblemeans being arranged in an equal number of rows and l columnsrepresenting `the identity and landing order of 4. A 'component asdefined in claim 3 including further means conditioned to derive asignal whenever a 'Said first tube is cut off and to apply thethus-derived n signal to all said electrically conducting' devices torender said assigned aircraft, respectively; and at least one manuallyoperable switch disposed in visual correspondence to each'row of saidsensible means to effect a change in f guidance of selected aircraft,whereby a hazard detected on said indicator and caused by a dangerousmaneuver of an aircraft may be expeditiously removed firstly bycorriparing the land-ing order of said hazard aircraft as it appears onsaid indicator with the *representation of said sensible means todetermine the range tracking rchannel corresponding to said hazardfaircraft, and subsequently by manually `actuating the switchcorresponding toA said hazard aircraft to effect a change in theguidance thereof. 11. Alvdevice responsive to a plurality of inputsignals for Aproducing a plurality of corresponding identificationsignalssuccessively in an order corresponding to the A' rality of inputsignals in the amplitudes are larger than a 17 magnitudes-of a Acommonvariable characteristic of said input signals, saiddevice comprising:means for generating a comparison signal having Vsaid commoncharacteristic ehanging-from one to the other of two predeterminedlimits, means for generating an identification signal for each of saidinput mon characteristic of said comparison signal becomes equal to thatof each of said input signals, a plurality of order registers, and meansfor introducing the first identification signal generated only to afirst order register, a second identification signal generated 'only toa second order register, etc., regardless orf-which specificidentification signal is generated first.

12. A unit for registering the identities of a plurality of inputsignals in the order of their magnitude,V said unit comprising: meansfor generating `a comparisonsignal signals each time saidcomchanging inamplitude from one to the other of the extreme variable limits of theinput signals, means for generating an identification signalcorresponding to each of 4the input signals eachtime said comparisonsignal becomes substantially equal in amplitude to each correspondinginput signal, a plurality of order registers, and means for introducingthe first identification signal generated only to a first orderregister, a second identification signal generated only to a secondorder register, etc., regardless of which specific identification signalis generated first.

13. The invention as defined in claim 12, wherein additional means areprovided to display visually the identities of the input signals in theorder in which their corresponding identification signals are generated.

14. A unit for registering the identities of a plurality of inputsignals in the order of their magnitude, said unit comprising: vmeansfor generating an initiating signal each time a different number ofinput signals arek produced; means for generating a comparison signaleach time said initiating signal is generated, said comparison signalchanging in amplitude from one to the other of the extreme variablelimits of the input signals, means for generating an identificationsignal corresponding to each of the input signals each time saidcomparison signal becomes equal in amplitude to -each correspondinginput signal; a plurality of order registers, and means for introducingthe first identification signal generated only to a first orderregister, a second identilication signal generated only to a secondorder register, etc., regardless of which specific identification signalis` generated first.

15. In a system forprearranging the identities of a plurality of inputsignals in order of their magnitude, a unit for operating a pluralityvof order registering devices, said unit comprising: means forgeneratinga comparison signal change in amplitude from one to the other of theextreme variable limits of the input signals, means for generating anidentification signal Vcorresponding to each of the input signals eachtime said comparison siggenerated, said selected order being the sameorder each time said comparison signal is generated.

16. In a system for rearranging the identities of a pluorder of theirmagnitudes, the combination comprising: means for generatingidentifica-tion signals corresponding to each of the input signals inthe order of their `amplitudes and at a time when their predeterminedminimum value, a plurality of order registers, and means for introducingthe first identification signal generated only to a first orderregister, a second ident' cation signal generated only to a second orderregister, etc., regardless of which specific identification signal isgenerated first.

17.` In a system for rearranging the identities of a pluthe combinationcomprising: means for generating a comparison signal changing inamplitude from one to the other of the extreme variable limits of theinput signals, second means for generating an identification signalcorresponding to each input signal assaid comparison signal becomessubstantially equal in amplitude to each input signal, a plurality oforder'registers, and third means for introducing'the'firstidentification signal generated only to a first order register, a secondidentification signal generated only to a second order register, etc.,regardless of which specific identification signal is generated first.

18. The invention as defined in claim 16, wherein said comparison signalis a sawtooth voltage.

19. The invention as defined in claim 16, wherein said comparison signalis generated each time a different number of input signals are produced.

2G. The invention as defined in claim 19, wherein v means areadditionally provided to remove the identities Vcontained in all of saidorder registers in excess of the number of input signals produced.

21. The invention as defined in claim 17, said second means including atrigger circuit for and responsive to each input signal to impress allof said identification signals on each of said order registers, saidthird means including a master order selector having means actuable inresponse to the generation of said identification signals to provideselectively return paths for said identification signals through only afirst order register upon the generation of a first identificationsignal, through only a second order register upon the generation of asecond identification signal, etc.

22. The invention as defined in claim 21, including means for settingsaid master order selector to provide a return path for thefirstidentification signal generated from only said first order register,each time a different number of input signals are produced.

23. The invention as defined in claim meansare additionally provided toremove contained in all of said order registers in number of the inputsignals.

24. In a track-while-scan landing system for controlling the descent ofa plurality of aircraft along an ideal glidepath, said system includinga channel for each of said aircraft to track the range of each, anarrangement to monitor simultaneously the descent of all of saidaircraft, said arrangement comprising: an indicator for producing avisual representation of the range of each of said aircraftsubstantially simultaneously in the same viewing area, sensible meansfor producing visual representations identifying said rangerepresentations with corresponding ones of said channels, said sensiblemeans lthereby being in the landing order of aircraft correspondingthereto, and at least one manually operable switch identifiable .witheach of said channels to effect a change in guidance of a selectedaircraft.

25. In a system for controlling a plurality of aircraft, the combinationcomprising: a separate channel corresponding to each aircraft, eachchannel being adapted to produce an output signal in accordance of eachcorresponding aircraft, all of said channels being operable to producesignals having a predetermined common range of values, whereby anychannel may be assigned to any aircraft having a position falling withina corresponding range of positions; means including a cathode-ray tuberesponsive to the output signals of said channels for producing positionindications corresponding to the relative positions of all of saidaircraft; means also responsive to said channel output signals forproducing indications to identify said channels in positions spacedapart in a predetermined direction in the same corresponding spacialorder of said position indications displayed on said cathode-ray tube inaccordance with said channel output signals; and a switch identifiablewith each of said 2l, wherein p with the position.

1,929,402v Belliveau Oct. 10, 1933 2,363,416 Henroteau Nov. 21,19442,391,469 Marshall Dec. 25, 1945 29 Preston A.. Y.--Apr\. 20, 1948`Sunstein July 26, 1949 VonMulinen May 30, 1950,- Rodgers Dec. 26,V 1950,Hildyard July 10,` 1951' Kelly June 16', 1953 Robbins Apr. 6, 1954`Glenn Aug. 9,1955

UNITED STATES PATENT OFFIQE CERTIFICATE OF CORRECTION Patent Noa2,932,812 April l2, l96O william T, o'Neil It is hereby certified thaterror appears in the printed specification of the above numbered patentrequiring correction and that the said Letters Patent should read ascorrected below.

Column l, line 55, after "producing" insert -m a column 2, line l2,after "from" insert the line I3, after "by" insert a Column 4, line 37,.for "the lamp" read one lamp line 42, for "push-buttons" read -fpushbuttons line 74, strike out "thaw: column 5, line 56, after "drops"insert a comma; column 7, line I7, before, "wipe" insert are positionedon line 18, strike out "portien"; line 2l, after supply" insert a comma;column 8, line ll, after "applied" insert a comme; line 47, after"executed" insert a comma; column 9, line 54, for "values ofcapacitance" read sizes of capacitor column lO, line l2, .for "triode106" read pentode lO7 line 22, for "17" read --ll7 column l2, line 38,after "channels" insert a comma; line 46, strike out "as a cathodefollower"; line 62, after "pulse" insert a comma; line 70, for "is" readare column I3, line 7, after "channel" insert a comma; line 8, after"energized" insert a comma; line 9, for "is" read are line l5, after"charged" insert a period same line, strike out "and"; line 16, for"after" read After same column 13, line 25, for "165 this" read l65 Thisline 37, after "closes" insert the line 48, for "Volts removed" readvolts are removed, 4, line 49, after "194 insert a comma; column 14,line 52, for "modulator" read modulated Column I7, line 53, for "change"read changing Signed and sealed this 8th day of November 1960,

(SEAL) Attest:

KARL n, AXLINE; l RoBERr C WATSON Attesting Officer Commissioner ofPatents

